/*
 * Copyright (c) 2003, 2004, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
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 */

package java.lang;

import java.io.IOException;

/**
 * An object to which <tt>char</tt> sequences and values can be appended.  The
 * <tt>Appendable</tt> interface must be implemented by any class whose
 * instances are intended to receive formatted output from a {@link
 * java.util.Formatter}.
 *
 * <p> The characters to be appended should be valid Unicode characters as
 * described in <a href="Character.html#unicode">Unicode Character
 * Representation</a>.  Note that supplementary characters may be composed of
 * multiple 16-bit <tt>char</tt> values.
 *
 * <p> Appendables are not necessarily safe for multithreaded access.  Thread
 * safety is the responsibility of classes that extend and implement this
 * interface.
 *
 * <p> Since this interface may be implemented by existing classes
 * with different styles of error handling there is no guarantee that
 * errors will be propagated to the invoker.
 *
 * @since 1.5
 */
public interface Appendable {

  /**
   * Appends the specified character sequence to this <tt>Appendable</tt>.
   *
   * <p> Depending on which class implements the character sequence
   * <tt>csq</tt>, the entire sequence may not be appended.  For
   * instance, if <tt>csq</tt> is a {@link java.nio.CharBuffer} then
   * the subsequence to append is defined by the buffer's position and limit.
   *
   * @param csq The character sequence to append.  If <tt>csq</tt> is <tt>null</tt>, then the four
   * characters <tt>"null"</tt> are appended to this Appendable.
   * @return A reference to this <tt>Appendable</tt>
   * @throws IOException If an I/O error occurs
   */
  Appendable append(CharSequence csq) throws IOException;

  /**
   * Appends a subsequence of the specified character sequence to this
   * <tt>Appendable</tt>.
   *
   * <p> An invocation of this method of the form <tt>out.append(csq, start,
   * end)</tt> when <tt>csq</tt> is not <tt>null</tt>, behaves in
   * exactly the same way as the invocation
   *
   * <pre>
   *     out.append(csq.subSequence(start, end)) </pre>
   *
   * @param csq The character sequence from which a subsequence will be appended.  If <tt>csq</tt>
   * is <tt>null</tt>, then characters will be appended as if <tt>csq</tt> contained the four
   * characters <tt>"null"</tt>.
   * @param start The index of the first character in the subsequence
   * @param end The index of the character following the last character in the subsequence
   * @return A reference to this <tt>Appendable</tt>
   * @throws IndexOutOfBoundsException If <tt>start</tt> or <tt>end</tt> are negative,
   * <tt>start</tt> is greater than <tt>end</tt>, or <tt>end</tt> is greater than
   * <tt>csq.length()</tt>
   * @throws IOException If an I/O error occurs
   */
  Appendable append(CharSequence csq, int start, int end) throws IOException;

  /**
   * Appends the specified character to this <tt>Appendable</tt>.
   *
   * @param c The character to append
   * @return A reference to this <tt>Appendable</tt>
   * @throws IOException If an I/O error occurs
   */
  Appendable append(char c) throws IOException;
}
